Guardrails: Fix update error for validator

[AkhileshNegi]

Is your feature request related to a problem?
When setting up the topic relevance guardrail, updating it causes an error, disrupting the workflow.

Describe the solution you'd like
Fix the update error for the topic relevance validator.

• Access Guardrails in Kaapi Konsole
• Edit the existing topic relevance validator
• Modify on-fail-action
• Save the configuration and ensure no error occurs

Original issue

Is your feature request related to a problem?
When the topic relevance guardrail is set up, attempting to update it results in an error, causing disruption in workflow.

Describe the solution you'd like
Fix the error that occurs when trying to update the topic relevance validator.

• Go to Guardrails in Kaapi Konsole
• Edit an existing topic relevance validator
• Change on-fail-action
• Save config and an error pops up

Screenshots